http_auth_random.rs

// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use log::trace;
use proxy_wasm::traits::*;
use proxy_wasm::types::*;
use std::time::Duration;

#[no_mangle]
pub fn _start() {
    proxy_wasm::set_log_level(LogLevel::Trace);
    proxy_wasm::set_http_context(|_, _| -> Box<dyn HttpContext> { Box::new(HttpAuthRandom) });
}

struct HttpAuthRandom;

impl HttpContext for HttpAuthRandom {
    fn on_http_request_headers(&mut self, _: usize) -> Action {
        self.dispatch_http_call(
            "httpbin",
            vec![
                (":method", "GET"),
                (":path", "/bytes/1"),
                (":authority", "httpbin.org"),
            ],
            None,
            vec![],
            Duration::from_secs(5),
        )
        .unwrap();
        Action::Pause
    }

    fn on_http_response_headers(&mut self, _: usize) -> Action {
        self.set_http_response_header("Powered-By", Some("proxy-wasm"));
        Action::Continue
    }
}

impl Context for HttpAuthRandom {
    fn on_http_call_response(&mut self, _: u32, _: usize, body_size: usize, _: usize) {
        if let Some(body) = self.get_http_call_response_body(0, body_size) {
            if !body.is_empty() && body[0] % 2 == 0 {
                trace!("Access granted.");
                self.resume_http_request();
                return;
            }
        }
        trace!("Access forbidden.");
        self.send_http_response(
            403,
            vec![("Powered-By", "proxy-wasm")],
            Some(b"Access forbidden.\n"),
        );
    }
}